Rainbow Electronics MAX1400 - Manual

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MAX1400
+5V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
________________________________________________________________ Maxim Integrated Products 1
19-1430; Rev 0; 2/99
General Description
The MAX1400 18-bit, low-power, multichannel, serial-
output ADC uses a sigma-delta modulator with a digital
decimation filter to achieve true 16-bit accuracy. The
user-selectable decimation factor of the digital filter
allows the conversion resolution to be reduced in
exchange for a higher output data rate. The device
achieves true 16-bit performance at an output data rate of
up to 480sps. In addition, the modulator sampling
frequency may be optimized for either lowest power
dissipation or highest throughput rate. The MAX1400
operates from +5V.
This device offers three fully differential input channels
that can be independently programmed with a gain
between +1V/V and +128V/V. Furthermore, it can com-
pensate an input-referred DC offset (such as system off-
set) up to 117% of the selected full-scale range. These
three differential channels may also be configured to
operate as five pseudo-differential input channels. Two
additional, fully differential system-calibration channels
are provided for gain and offset error correction. External
access is provided to the multiplexer (mux) output to
facilitate additional signal processing.
The MAX1400 can be configured to scan all signal inputs
sequentially and provide the results through the serial
interface with minimum communications overhead. When
used with a 2.4576MHz or 1.024MHz master clock, the
digital decimation filter can be programmed to produce
zeros in its frequency response at the line fre-
quency and associated harmonics, ensuring excellent
line rejection without the need for further post-filtering.
The MAX1400 comes in a 28-pin SSOP package.
Applications
Portable Industrial Instruments
Portable Weigh Scales
Loop-Powered Systems
Pressure Transducers
Features
♦ 18-Bit Resolution, Sigma-Delta ADC
♦ 16-Bit Performance with No Missing Codes
to 480sps
♦ Low Quiescent Current
250µA (operating mode)
2µA (power-down mode)
♦ 3 Fully Differential or 5 Pseudo-Differential Signal
Input Channels
♦ 2 Additional Fully Differential Calibration
Channels/Auxiliary Input Channels
♦ Access to the Mux Output/ADC Input
♦ Programmable Gain and Offset
♦ Fully Differential Reference Inputs
♦ Converts Continuously or On Command
♦ Automatic Channel Scanning and Continuous
Data Output Mode
♦ Operates with +5V Analog Supply and
+3V or +5V Digital Supply
♦ SPI™/QSPI™-Compatible 3-Wire Serial Interface
♦ 28-Pin SSOP Package
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
SCLK
DIN
DOUT
INT
V DD
DGND
AIN5
CALOFF+
CALOFF-
REFIN+
REFIN-
CALGAIN+
CALGAIN-
AIN6
AIN4
AIN3
AIN2
AIN1
V+
AGND
ADCIN-
ADCIN+
MUXOUT-
MUXOUT+
RESET
CS
CLKOUT
CLKIN
SSOP
TOP VIEW
MAX1400
SPI and QSPI are trademarks of Motorola, Inc.
Pin Configuration
Ordering Information
PART
MAX1400CAI
MAX1400EAI -40°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
28 SSOP
28 SSOP